Abstract
Urdbean leaf crinkle Virus (ULCV), an unclassified virus, seed-borne with narrow host range and probably aphid-transmitted, is relatively a destructive and serious disease of urdbean than other viruses infecting legumes in Pakistan. Urdbean germplasm consisting of 87 genotypes was screened against the virus under field conditions during spring and summer seasons 2005-06. More than 50% of the genotypes were infected during initial period of 3-4 weeks followed by slow down of infection. Eight genotypes viz., Mash-1, 6049-7-1, 9049-1, AARIM-174, AARIM-191, AARIM-220, 4cm-719, and 90cm-056 showed variable response to ULCV in both the seasons probably due to their genetic instability. On the basis of 0-5 disease rating scale and disease severity index, genotypes varied significantly in their reaction against ULCV. Nine genotypes viz., 2cm-703, 90cm-015, 93cm-006, 94cm-019, 99cm-001, IAM 382-1, IAM382-9, IAM382-15 and IAM133 remained free of infection and were classified as "Highly Resistant". Rest of the genotypes were infected, among which 19 were classified as "Resistant", 29 as "Moderately Resistant", 11-19 as "Moderately Susceptible 3-6 as "Susceptible and 4-6 were highly susceptible. Some genotypes in spite of high disease pressure were good yielder, indicating a high degree of tolerance to ULCV with desirable quality for breeding.